prevent label clashes in Django 1.7

if there are multiple apps in the same project that end with ``.django`` there will be a label clash.
Merge remote-tracking branch 'origin/master' into feature/prevent-django-1.7-label-clashes
Add missing __future__ import to pass coding guidelines.
Merge pull request #525 from getsentry/feature/prevent-django-1.7-label-clashes

prevent django 1.7 label clashes